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 A034293 Numbers k such that 2^k does not contain the digit 2 (probably finite). 9
 0, 2, 3, 4, 6, 12, 14, 16, 20, 22, 23, 26, 34, 35, 36, 39, 42, 46, 54, 64, 74, 83, 168 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Is 168 the last term? First row of A136291. - R. J. Mathar Apr 29 2008 Equivalently, indices of zeros in A065710. - M. F. Hasler, Feb 10 2023 LINKS Table of n, a(n) for n=1..23. FORMULA The last term is A094776(2), by definition. - M. F. Hasler, Feb 10 2023 EXAMPLE Here is 2^168, conjecturally the largest power of 2 that does not contain a 2: 374144419156711147060143317175368453031918731001856. - N. J. A. Sloane, Feb 10 2023 MAPLE isA034293 := proc(n) RETURN(not 2 in convert(2^n, base, 10)) ; end: for n from 0 to 100000 do if isA034293(n) then print(n) ; fi ; od: # R. J. Mathar, Oct 04 2007 MATHEMATICA Join[{0}, Select[ Range@10000, FreeQ[ IntegerDigits[2^# ], 2] &]] (* Shyam Sunder Gupta, Sep 01 2007 *)(* adapted by Vincenzo Librandi, May 07 2015 *) Select[Range[0, 10^4], DigitCount[2^#][[2]] == 0 &] (* Michael De Vlieger, Apr 29 2016 *) PROG (Magma) [n: n in [0..1000] | not 2 in Intseq(2^n) ]; // Vincenzo Librandi, May 07 2015 (PARI) is(n)=setsearch(Set(digits(2^n)), 2)==0 \\ Charles R Greathouse IV, May 10 2016 (PARI) is_A034293(n)=!foreach(digits(2^n), d, d==2&&return) \\ M. F. Hasler, Feb 10 2023 (Python) def is_A034293(n): return'2'not in str(2**n) [n for n in range(199) if is_A034293(n)] # M. F. Hasler, Feb 10 2023 CROSSREFS Cf. A007377. See also similar sequences listed in A035064. Cf. A065710, A094776. Sequence in context: A018309 A245481 A039038 * A136291 A128393 A368988 Adjacent sequences: A034290 A034291 A034292 * A034294 A034295 A034296 KEYWORD base,nonn AUTHOR Erich Friedman EXTENSIONS Edited by N. J. A. Sloane, Oct 03 2007 Removed keyword "fini" since it is only a conjecture that this sequence contains only finitely many terms. - Altug Alkan, May 07 2016 STATUS approved

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Last modified February 21 16:55 EST 2024. Contains 370237 sequences. (Running on oeis4.)